This invention relates to an engine provided with a rotary-speed control apparatus and an emergency halt apparatus.
Meant here by the rotary-speed control apparatus is such an apparatus that is installed in the intension of saving fuel from unnecessary consumption and accordingly abating the engine noise; by means of automatically lowering down the engine speed, when no substantial load acts on the engine, from a high-speed rotation for the normal working operation to a low-speed rotation for such idling operation; while automatically restoring the engine to the normal working operation, when the load beyond a preset threshold value has again acted on the engine.
On the other hand, meant by the emergency halt apparatus is such an apparatus that is installed in the intention of preventing damage of the engine, as seizure or the like, by means of mergently halting the engine in response to detecting any abnormality of various factors influencing the normal engine operation, for instance as abnormal lowering down of the lubricant oil pressure and abnormal rising up of the cooling water temperature.
More specifically, this invention relates to an engine having as its prerequisite to this invention the construction of the ancillary apparatuses basically prevailing in every engine shown in either one of FIGS. 1, 2 and 9, as follows:
Thus, the engine 1 is provided with the rotary-speed control apparatus 2 and the emergency halt apparatus 3, such that:
the rotary-speed control apparatus 2 comprises: PA0 and PA0 functions so as to maneuver an acceleration lever 7, by means of the rotary-speed switchover actuator 6: PA0 and PA0 the emergency halt apparatus 3 comprises: PA0 functions so as to halt operation of the engine 1 by means of the engine-halt actuator 13, in response to occurrence of any abnormality in the engine 1, PA0 a restoring spring 39, the engine-halt actuator 13 and the rotary-speed switchover actuator 6 are interlockedly connected to the accelerator lever 7, in such a manner that the accelerator lever 7 is amneuvered: PA0 the rotary-speed control circuit 5 of the rotary-speed control apparatus 2 is connected to an electric power source 33 via: PA0 a control input line 64 of the emergent halt control circuit 12 of the emergency halt apparatus 3 is connected to the power source 33 parallelly via:
a load detection circuit 4, PA1 a rotary-speed control circuit 5 and PA1 a rotary-speed switchover actuator 6, PA1 which are connected one after another in this sequential order, PA1 into a high-speed rotation position 8 when the engine 1 is in a state of loaded operation, PA1 into a low-speed rotation position 9 when the engine 1 is in a state of no-load operation, which state is detected and communicated in the same manner as mentioned above; and PA1 an abnormality detection apparatus 11, PA1 an emergent halt control circuit 12 and PA1 an engine-halt actuator 13, PA1 which are connected one after another in this sequential order, PA1 and PA1 which occurrence is detected by the abnormality detection apparatus 11 and communicated to the emergent halt control circuit 12. PA1 into an engine-halting position 10 as is resiliently urged there by means of the restoring spring 39, when both the actuators 6,13 are left deenergized, PA1 into the low-speed rotation position 9, when only the engine-halt actuator 13 alone is energized, PA1 and PA1 into the high-speed rotation position 8, when both the actuators 6,13 are energized together; PA1 an electric wire 31 or 32 and PA1 the emerbent halt control circuit 12 of the emergency halt apparatus 3, PA1 in such a manner that: PA1 an ON position 38 and PA1 a starter position 37 of a main switch 34; PA1 in such a manner that the accelerator lever 7 is automatically maneuvered into the low-speed rotation position 9,
which state is detected by the load detection apparatus 4 and is communicated to the rotary-speed control circuit 5, PA2 the electirc power supply is effected from the power source 33 to the rotary-speed control circuit 5 through the emergent halt control circuit 12, PA2 when the main switch 34 is maneuvered into the starter position 37 to thus provide the engine-starting state, PA2 on account that:
Shown in FIG. 1 is a typical example of the conventional construction of the rotary-speed control apparatus and the emergency halt apparatus for the engine of the above-mentioned type.
As seen, the rotary-speed control apparatus 2 and the emergency halt apparatus 3 are annexed to the engine 1, independently of each other.
The accelerator lever 7 is urged into the high-speed rotation position 8 by means of a high-speed biasing spring 14, and is driven thereagainst in switchover into the low-speed rotation position 9 by means of the rotary-speed switchover actuator 6. Shown at 15 is an engine-halt lever, and it is urged into an engine-operating position a by means of a halt-releasing spring 16, and is driven thereagainst into an engine-halting position b by means of the engine-halt actuator 13.
The rotary-speed control circuit 5 and the emergent halt control circuit 12 are connected, independently of each other, to a battery electric power source 17 as well as a generator 18 which is an accessory part to the engine 1.
Shown at 19 is a main switch, at 20 is a timer, at 21 is a generator driven by the engine, at 22 is (are) load appliance(s), and at 23 is a manual low-speed-setting lever.
FIG. 1 shows the state with the engine 1 at a standstill.
Function of the apparatuses of the above construction is now described hereunder. In the illustrated state, the main switch 19 is at an OFF position c, and so neither the rotary-speed control apparatus 2 nor the emergency halt apparatus 3 is supplied with electric power. In this consequence, the accelerator lever 7 is held as maneuvered into the high-speed rotation position 8 by means of the high-speed-biasing spring 14, and the engine-halt lever 15 is held as maneuvered into the engine-operating position a by means of the halt-releasing spring 16.
By switching over the main switch 19 in the sequential order of a preheating position d, a starter position e and an ON position f, while manually maneuvering the accelerator lever 7 into the low-speed rotation position 9 by means of the manual low-speed-setting lever 23, there starts the engine 1 by means of a non-illustrated self-starter. After the starting, the generator 18 is driven by the engine 1 at a sufficient speed as to start generating electricity to give sufficient triggering base petentials to transistors 26,27 of the rotary-speed control circuit 5 and the emergent halt control circuit 12, respectivelly. The transistor 26 thus turns ON and makes ON a relay 28. Accordingly, the rotary-speed switchover actuator 6 is energized and moves rightwards as shown by an arrow in FIG. 1, thus to retain the accelerator lever 7 in the low-speed rotation position 9. Hereafter, the operator may release the manual low-speed-setting lever 23.
When there acts no load on the engine 1, it then is truly the case, as mentioned just above, that as the transistor 26 turns ON because of the triggering base vlotage, it makes ON the relay 28, causes the rotary-speed switchover actuator 6 to move rightwards, displaces the accelerator lever 7 into the low-speed rotation position 9, and causes the engine 1 to operate in a low-speed rotation.
However, if there acts the load on the engine 1, then the load detection apparatus 4 emits a load-detection signal sufficient enough to act as triggering base potential of a transistor 29 which is thus thereby turned ON and which then in turn substantially grounds the base potential of the transistor 26 and therefore turns OFF sequentially the transistor 26, the relay 28 and the rotary-speed switchover actuator 6. Then, the accelerator lever 7 is maneuvered into the high-speed rotation position 8 by means of the high-speed-biasing spring 14, and it causes the engine 1 to operate in a high-speed rotation.
All what is stated hereinabove is the function as proceeds under normal operation of the engine 1, but on the other hand if abnormality occurs during operation of the engine, then the abnormality detection apparatus 11 turns ON. Hereupon, the transistor 27, supplied with the sufficient triggering base potential as has been described hereinabove, is turned ON concurrently with a relay 30 which in turn causes the engine-halt actuator 13 to move rightwards as shown by an arrow in FIG. 1, thus to maneuver the engine-halt lever 15 into the engine-halting position b and therefore to cause the engine 1 to halt.
Besides, if the main switch 19 is maneuvered into the OFF position c, then the timer 20 is energized and kept ON for a set period, to thereby cause the engine-halt actuator 13 to move rightwards during such set period and therefore to cuase the engine 1 to halt. Upon lapsing of the set period, the timer 20 breaks OFF and therefore blocks the power supply to the engine-halt actuator 13, thus to prevent the actuator 13 from burning out.
With this conventional structure, there are following drawbacks:
In the case there occurs any damage or disorder in the emergent halt control circuit 12, for instance as the breaking damage of the transistor 27 in that circuit 12 or of lead wires 24 connecting to the transistor 27, then the relay 30 fails to make ON even if there has occurred any abnormality at the engine 1, as abnormal lowering down of the lubricant oil pressure, abnormal rising up of the cooling water temperature, or the like, and even if the abnormality detection apparatus 11 turns ON in due response to such abnormality. Because of such failure in the intended operation of the relay 30, the engine-halt actuator 13 can not be actuated, and the engine 1 can not then be emergently halted.
In this consequence, the engine 1 then continues operation in spite that the above-mentioned abnormality has occurred, and may therefore get broken, for instance as being burnt out on account of the failure of lubrication, cooling and the like.
Besides the operator is required to effect complicated maneuvering at the time of the starting up of the engine 1, namely, to manually maneuver the main switch 19 in sequential switchover, while concurrently maneuvering the accelerator lever 7 forcibly into the low-speed rotation position 9 by means of the manual low-speed-setting lever 23.